1. Field
The present disclosure relates to image sensors, such as image sensors having improved light utilization efficiency based on reflective color filters.
2. Description of the Related Art
A color display apparatus or a color image sensor generally displays images of various colors or detects colors of incident lights by using color filters. In a current color display device or a color image sensor, a RGB color filter mechanism is most popularly employed, in which, for example, green filters are disposed at two pixels from among four pixels and a blue filter and a red filter are respectively disposed at the other two pixels. Furthermore, other than the RGB color filter mechanism, a CYGM color filter mechanism may also be employed, in which cyan, yellow, green, and magenta color filters (complementary colors) are respectively disposed at four pixels.
However, a general absorptive color filter absorbs lights of colors other than a corresponding color, and thus light utilization efficiency may deteriorate. For example, in case of using RGB color filters, only one-third of an incident light is transmitted and two-thirds of the incident light is absorbed, and thus the light utilization efficiency is only about 33%. Therefore, in a color display apparatus or a color image sensor, most light loss occurs in relation to color filters.
Recently, to improve light utilization efficiency of a color display apparatus or a color image sensor, there have been attempts to use a color separation element instead of color filters. A color separation element may separate colors of an incident light by using a diffraction characteristic or a refraction characteristic that differs based on wavelengths, and colors separated by the color separation element may be transmitted to corresponding pixels, respectively. However, a color separation element is still unable to provide images as clear as images provided by using color filters.